Ruthenium Complex Useful as Sensitizer, Dye-Sensitized Oxide Semiconductor Electrode and Solar Cell Using Same
This invention relates to a ruthenium complex having an organic ligand and to an electrode having a surface on which such a metal complex has been adsorbed. The present invention is also directed to a solar cell using such an electrode.
One known solar cell uses an oxide semiconductor electrode containing titanium oxide. It is also known to adsorb a sensitizing dye capable of absorbing a light of a visible region on such an electrode for the purpose of improving light energy absorbing efficiency thereof. The known sensitizing organic dye is, however, not fully satisfactory, because the wavelength region of light which can be absorbed by the dye is not sufficiently broad and because the coefficient of absorption of the dye is not high.
It is, therefore, the prime object of the present invention to provide a ruthenium complex which can efficiently absorb solar light of a long wave length region and which is useful as a sensitizer.
Another object of the present invention is to provide a dye-sensitized oxide semiconductor electrode using the above sensitizer.
It is a further object of the present invention to provide a solar cell using the above electrode, which has a high photoelectric conversion efficiency.
In accomplishing the foregoing objects, there is provided in accordance with the present invention a ruthenium complex represented by the following formula:
xe2x80x83RuL1L2X
wherein
L1 represents a 2,2xe2x80x2-6xe2x80x2,2xe2x80x3-terpyridine compound having at least one group selected from the group consisting of a carboxyl group, a salt of a carboxyl group, a sulfonic acid group, a salt of a sulfonic acid group, a phosphoric acid group and a salt of a phosphoric acid group, L2 represents a diketonate ligand represented by the following formula: 
wherein R1 and R2 are independently selected from alkyl, alkoxyalkyl, aninoalkyl, perfluoroalkyl and aryl, R3 represents a hydrogen atom, alkyl, alkoxyalkyl, aminoalkyl, perfluoroalkyl and aryl, and X represents a monodentate ligand selected from the group consisting of a halide (halogen), a cyano group, a thiocyano group and a thiolate.
In another aspect, the present invention provides a dye-sensitized oxide semiconductor electrode comprising an electrically conductive body, an oxide semiconductor film provided on a surface of said electrically conductive body, and the above ruthenium complex adsorbed on said film.
The present invention also provides a solar cell comprising the above dye-sensitized oxide semiconductor electrode, a counter electrode, and a redox electrolyte contacting with said dye-sensitized oxide semiconductor electrode and said counter electrode.